1. Field of the Invention
The present invention relates to a zoom lens with a vibration reduction function and, more particularly, to a vibration reduction method for zoom lenses for a still camera, video camera, and the like.
2. Related Background Art
A conventional zoom lens with a vibration reduction function corrects a variation in image position caused by, e.g., a camera shake by shifting an arbitrary lens group in the zoom lens constituted by two or more lens groups in a direction substantially perpendicular to the optical axis, as described in Japanese Laid-Open Patent Application Nos. 1-189621 and 1-191113. Also, another zoom lens with a vibration reduction function corrects a variation in image position caused by, e.g., a camera shake by shifting a partial lens group in a fixed first lens group upon zooming (variable magnification) in a direction substantially perpendicular to the optical axis, as described in Japanese Laid-Open Patent Application No. 1-284823.
Note that correcting a variation in image position caused by, e.g., a camera shake by shifting the lens group in a direction substantially perpendicular to the optical axis will be referred to as "vibration reduction" in this specification.
However, the above-mentioned zoom lenses are not suitable for a lens for a still camera or a video camera since a sufficient back focus cannot be assured and a large zoom ratio cannot be realized for a lens for a single-lens reflex camera or a lens for a video camera.
Since vibration reduction is achieved using a movable lens group upon zooming (variable magnification) or a largest one of lens groups constituting the zoom lens, mechanisms undesirably become bulky and complicated.